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How do you increase white blood cells during chemo?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on May 31, 2022.

Official answer


Your doctor may prescribe a medicine known as a colony stimulating factor to boost your white blood cell count if you are having chemotherapy ("chemo"). Chemo drugs work by killing rapidly growing cancer cells, but blood levels of white blood cells (known as neutrophils) may also decrease. Neutrophils help to fight infection in your body. Lower levels of these white blood cells can increase your risk for infection, especially during chemotherapy.

Febrile neutropenia is a dangerous condition that may occur during chemotherapy when a fever occurs along with a drop in the number of white blood cells. Your risk of infection increases if you have neutropenia during chemotherapy. Neutropenia occurs when the neutrophil count is less than 2000.

Colony stimulating factors can help to prevent the occurrence of neutropenia, and can help you stay on track with your cancer treatments. Not everyone needs medicine to increase their white blood cells during chemotherapy.

What are colony stimulating factors?

Colony stimulating factors are proteins that can help to prevent the occurrence of febrile neutropenia, a condition that can lead to infections because of low numbers of white blood cells. They help to boost the numbers of white blood cells in your body. Febrile neutropenia may result in hospitalization in many patients.

Pegfilgrastim is a common colony stimulating factor used to help prevent febrile neutropenia. Pegfilgrastim is a “PEGylated” form of filgrastim (Neupogen), meaning it is attached to a chemical called polyethylene glycol (PEG). PEGylated forms of filgrastim can be given less frequently because they are removed from the body more slowly.

Several biosimilars to Neulasta are now approved. A biosimilar is highly similar to an already approved FDA-approved biologic (known as the reference product) with no clinically meaningful differences in terms of safety, purity and potency.

Biosimilars can provide cost effective treatment options to already approved biologics. Biosimilar names differ slightly with extra letters added at the end of “pegfilgrastim” to help identify these products as biosimilars.

More information: What Are Biosimilars? Top Facts You May Not Know

Pegfilgrastim colony stimulating factors include:

  • Neulasta (pegfilgrastim), from Amgen, the first pegfilgrastim approved by the FDA in 2002.
  • Fulphila (pegfilgrastim-jmdb) from Mylan, was the first biosimilar to Neulasta approved in June 2018.
  • Udenyca (pegfilgrastim-cbqv), a biosimilar from Coherus BioSciences, was approved in November 2018.
  • Ziextenzo (pegfilgrastim-bmez), a biosimilar from Sandoz, was approved in November 2019.
  • Nyvepria (pegfilgrastim-apgf), a biosimilar from Pfizer, was cleared by the FDA in June 2020.
  • Fylnetra (pegfilgrastim-pbbk), a biosimilar from Amneal Pharmaceuticals, was approved in May 2022.

Like Neulasta, all biosimilar products are PEGylated growth colony-stimulating factors used to reduce the duration of febrile neutropenia (fever or other signs of infection with a low count of white blood cells) in patients treated with chemotherapy in certain types of cancer. These agents help to lower the risk of infection due to a low white blood cell count.

How are colony stimulating factors given?

Colony stimulating factors are given as a subcutaneous injection under the skin. Neulasta can also be given as an injection through an on-body injector (called the Neulasta Onpro) that prevents you from having to return to the clinic the day after your chemo for a shot.

In some cases, your doctor may also recommend that you can be taught to give the injection at home using the prefilled syringe when an on-body injector is not available.

You should not inject a dose of pegfilgrastim or an associated biosimilar to children weighing less than 45 kg (less than 99 lb) from a prefilled syringe. An accurate dose cannot be measured using the prefilled syringe in this weight group.

The most common side effects are bone pain and pain in extremity, but these are not all the possible side effects. Talk to your healthcare provider for medical advice about side effects.

Neulasta and Neulasta Onpro

Neulasta is given as a subcutaneous (under the skin) injection once every chemotherapy cycle. Neulasta should be injected at least 14 days before and 24 hours after your dose of chemotherapy.

Neulasta is given either as an injection from a prefilled syringe or by using the on-body injector (OBI) for Neulasta (Neulasta Onpro) for use at home, which your doctor can apply to your skin right after chemo. Twenty-seven hours after the OBI has been placed on the skin, the OBI will automatically deliver a dose of Neulasta over a 45 minute period. After your dose is complete, you can remove the injector and dispose of it using the instructions your healthcare provider will supply.

In some cases, you or your caregiver may be able to give the prefilled syringe injection at home if you do not have access to the Neulasta Onpro or cannot return to the doctor the next day. Also, receiving your dose at home may reduce the risk of coming into contact with viruses or bacteria that could increase your risk for infection.

Fulphila, Udenyca and other biosimilars

The biosimilars to Neulasta are also given as a subcutaneous (under the skin) injection once every chemotherapy cycle. They should be injected at least 14 days before and 24 hours after your dose of chemotherapy.

The pegfilgrastim biosimilars to Neulasta are given by your healthcare provider as a subcutaneous injection under your skin. Biosimilars are not available with an on-body injector device at this time. These products are available as single-dose prefilled syringes for subcutaneous use (injected under the skin).

Your healthcare provider may suggest that the injection from a prefilled syringe can be given at home by you or your caregiver. Your healthcare provider will show you how to administer the injection if you use it at home. Also, follow the detailed “Instructions for Use” that comes with your product information on how to prepare and inject your dose if you use it at home. If you have questions, call your doctor immediately.

This is not all the information you need to know about Neulasta, pegfilgrastim or the corresponding biosimilars for safe and effective use. Review the full product information specific to your medicine and discuss any questions you have with your doctor, prescriber or other health care provider.


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